Ecotypes of Slender Spikerush (Eleocharis acicularis) and Their Response to MCP Herbicide

This experiment was conducted to investigate the control rating of MCP to slender spikerush collected from several regions (Kagoshima, Fukuyama, Zentsuji, Tsu, Kanazawa and Takada) in Japan, from the view point of the difference of the weed ecotype. The following results were shown. (1) The overwintering organ of slender spikerush was divided into two types. One is the well-developed bud which is formed on the base of discolored long leaves (Kagoshima, Tsu, Kanazawa and Takada, See Fig. 1-1), and the other is poor-developed bud formed on the base of green adult leaves (Fukuyama, See Fig. 1-2). (2) The growth condition of overwintering buds of slender spikerush from Kagoshima, Fukuyama and Zentsuji in early spring season was more viable than ones from Tsu, Kanazawa and Takada, and such phenomenon was remarkable under the low temperature than high temperature conditions. (3) The effectiveness of MCP was clearly different among slender spikerushes from different locality, and became larger in the order, Fukuyama, Takada, Kanazawa, Kagoshima. Such phenomenon was also observed even under the different conditions of the growth or temperature after MCP treatment.